docs: def image_corner(self, corner):
          """Return image corner in pixels, as shapely.Point."""
          if corner not in self.corner_types():
              raise GeoRaster2Error('corner %s invalid, expected: %s' % (corner, self.corner_types()))
  
          x = 0 if corner[1] == 'l' else self.width
          y = 0 if corner[0] == 'u' else self.height
          return Point(x, y)